| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass filter exhibiting sufficient strength even when it is thinned.SOLUTION: The optical glass filter contains, by weight ratio in terms of oxide, SiO50 to 70%, BO0 to 14%, AlO0 to 4%, LiO 0 to 4%, NaO 5 to 20%, KO 5 to 10%, BaO 0 to 10%, and contains one or more component of CeO0 to 5%, TiO0 to 10%, CoO 0 to 10%, ZnO 0 to 10% and no ZrOand has such a strength that it does not break down even in an impact test in which a steel ball having weight of 111.9 g is gravity dropped from height of 1.27 m to a sample with above described composition and formed into a flat plate having a thickness of 2 mm by optical polishing.SELECTED DRAWING: Figure 2 |
